Retinitis pigmentosa (RP) is a genetically heterogeneous disorder characterized by death of the light-sensing photoreceptor cells of the outer neural retina. Although collectively quite common, individually each disease- causing gene is quite rare. Three genes, USH2A, ABCA4 and RHO, account for a large portion of disease and elicit a wide-range of RP clinical phenotypes caused by an array of different disease-causing mutations. In this proposal we will use CRISPR/Cas9-mediated genome editing to target and correct three different classes of disease-causing mutations: 1) an intronic cryptic splice site mutation in USH2A; 2) an exonic coding sequence mutation in ABCA4; and 3) a dominant gain-of-function mutation in RHO. Using a CRISPR-based strategy will allow for disease-causing genes to remain under control of their endogenous promoters, allow for correction of large genes not amenable to gene replacement therapy and provide an avenue to `turn off' harmful dominant gain of function mutations. These genome-editing approaches will be tested on patient-derived induced pluripotent stem cells with molecularly confirmed mutations. Correcting cells that harbor a disease-causing mutation will allow for generation of cells for future autologous transplantation studies in human patients. The studies outlined in this proposal will pave the way for a new gene augmentation and stem cell-based therapeutic avenues for treatment of retinitis pigmentosa.